Enhanced 3D printed Al2O3 core via in-situ mullite

The ceramic core plays an important role in the preparation of aero-engine hollow blades, as it can directly determine the precision and pass rate of the cooling passage in the blade cavity. Sufficient high-temperature bending strength, high open porosity, and low sintering shrinkage are the main requirements for qualified ceramic cores. In order to prepare qualified ceramic cores with complex structures, in-situ mullite-reinforced Al2O3-based ceramic cores were successfully prepared using vat photopolymerization 3D printing technology. The in-situ synthesis of mullite was designed through thermodynamic analysis. The influence mechanisms of the sintering temperature and doping amount of fused silica on the open porosity, sintering shrinkage, and bending strength of the core were systematically investigated. With an increase in the sintering temperature and doping amount of fused silica, the porosity of the in situ mullite-reinforced ceramic core decreased. Sintering shrinkage increased with an increase in the sintering temperature and doping amount of fused silica. The cores containing 20 wt% fused silica showed the smallest sintering shrinkage. The bending strength increased with an increase in the sintering temperature and the doping amount of fused silica. A core doped with 20 wt% fused silica had the highest bending strength at 1773.15 K. Furthermore, 20 wt% fused silica doping, sintered at 1673.15 K, can be used to prepare in-situ mullite enhanced Al2O3-based cores with the best comprehensive properties. This core has a higher open porosity (40%), suitable bending strength of 25 MPa (at 1773.15 K), and lower sintering shrinkage in the Z direction. The significance of this study lies in the regulation of in-situ mullite generation and viscous flow in solid-liquid sintering by adjusting the doping amount of fused silica and the sintering process, and this opens up new pathways by the coordinated regulation of strength, open porosity, and sintering shrinkage of 3D printed ceramic cores.

Automated summary

This study successfully prepared Al2O3-based ceramic cores with mullite reinforcement using 3D printing technology. By adjusting the sintering temperature and doping amount of fused silica, the in-situ synthesis of mullite was achieved. The resulting cores exhibited improved properties, such as higher open porosity, suitable bending strength, and reduced sintering shrinkage.